Magnesium base alloy



Patented Feb. 25, 1 941 UNITED STATES I I 2,232,922 -MAGNESIUM BASE ALLOY John 0. McDonald, Midland, Mich, assignor to The Dow Chemical Company, Midland, Mich, a corporation of Michigan No Drawing. Application January 31, 1940, Serial No. 316,514

3 Claims.

The invention relates .to magnesium base alloys, and more particularly concerns'an alloy of this nature having a high degree of formability associated with other desirable physical proper- 5 ties such as excellent yield and tensile strengths. Magnesium alloys are being widely used in the various structural and. mechanical arts where a light weight metal is highly desirable, such as for use in making castings, forgings, and the like;

However, the use of these alloys in the rolled form to make sheet metal articles requiring forming operations, such as bending, drawing and the like, has not progressed as rapidly due to the fact that in general alloys of good formability permitting relatively sharp bends to be .made without the article developing external cracks usually have inferior strength characteristics.

It is accordingly the principal object of the invention to provide a magnesium base alloy which can be made into rolled sheet or the like possessing a sufficient degree of ductility or formability to be sharply bent, drawn, or otherwise shaped while having good tensile and yield strengths.

Other objects and advantages will be apparent from about 1 to 5 per centof silver and from 0.1 to 0.3 per cent of calcium. The specific proportion of each alloying metal and the total amount of alloying metals to be added to the new alloy depends upon the use for which the alloy is intended. For example, where good ductility or formability associated with excellent yield and tensile strengths is of principal importance, the alloy should preferably contain from about 4 to 8 per cent of silver and from 0.1 to 0.2- per cent of calcium. While in those instances where exceptionally high yield and tensile strengths are more important, the alloy should contain from 10 to per cent of silver and from 0.1 to.0.3 per cent of calcium.

The'following table lists some of the properties of rolled sheet metal made from my new ternary alloy and compares these properties with those of rolled sheet made from related binary alloys. A comparison of the properties illustrates the improvement in the strength characteristics of the new alloy over that of the closely related binary alloy. In the table the per cent elongation is to be regarded as a measure of the as the description of the invention proceeds. ductility or forma bility of the specimen.

Table Nomllitiialciohm- 011 11mm Annealed Cold rolled (magnesiumremainder) Yield Tensile Percent Yield Tensile Ag Ca strengthin strengthln elongation strengthm strengthm lbsJsq. in. lbs./sq. in. in 2 inches lbs./sq. 1n lbs/sq. 111.

0.15 18,000 32,000 17 29,000 35,000 2 1 ,000 32,000 13 22,000 35,000 2 0.15 1,000 32,000 17 35,000 40,000 4 21,000 34,000 20 33,000 30,000 4 0.15' 20,000 35,000 18 30,000 45,000 40 s 25, 000 38,000 10 37, 000 44,000 a 0.15 24,000 38.000 13 43,000 52,000 12 27,000 42,000 3 39,000 47,000 12 0.15 27,000 r 41,000 7 44,000 55,000

My invention resides in the discovery that a The properties listed in the above table under magnesium base alloy composed of from 0.1 to 20 per cent of silver and from 0.01 to 1. per cent of calcium, the balance being substantially all range of the composition indicated, I have found that in general the preferred combination of properties is obtained when the alloy contains the section headed by the term annealed were obtained by first rolling the alloys at a temperature of 600 F. and thereafter annealing them at various temperatures, in the temperature range from 400 to 600 F; The properties selected for the table were those of the annealed speci-' mens which exhibited the maximum elongation. Properties listed in the above table under the section headed cold'rolled were obtained by subjecting specimens of the alloy which had been hot rolled. a a temperature of 600 F. to addiit will be noted that the alloys containing lower percentages of alloying ingredients have an ex-' cellent elongation coupled with markedly superior strength properties in the cold rolled state.

In the higher percentages of alloying ingredients,

the strength characteristics of the new alloy. in

' the cold rolled state also show a high degree of improvement. Similar improvement will be noted throughout the range of alloyingr ingredients indicated.

While the new alloy is most useful in the wrought form, such as sheets, due to its formability characteristics; it may also be suitably used in making castings, forgings. extruded forms and the like. It is further pointed out that my new alloy is amenable to solution and precipitation heat treatments, which, according- I be present in the flux without exerting anydeleterious efiects, but in this case it is preferable to, add thecalcium last without too much stirring or agitation in order to prevent the loss of some of the calcium into the flux.

I claim:

1. A magnesium base alloy containing from 0.1 to 20 per cent of silver, from 0.01 to 1 per cent of calcium, the balance being substantially all magnesium.

2. A magnesium base alloy containing from- 2 to 8 per cent of silver and from 0.1 to 0.2 per cent of calcium, the balance being magnesium.

3. A magnesium base alloy containing from 8 to 15 per cent of silver and from 0.15 to 0.3 per cent of calcium, the balance being magnesium.

JOHN C.'MCDONAID. 

